1. Field of the Invention
The present invention relates to a linear guide apparatus including a guide rail and a slider linearly movable along the guide rail through a multiplicity of rolling members and, in particular, to an oil leakage preventing structure of a linear guide apparatus for preventing leakage of lubricating oil supplied to the rolling members from the slider.
2. Description of the Relevant Art
Prior art oil leakage preventing structures of a linear guide apparatus of this type are disclosed, for example, in Japanese Utility Model Laid-Open Publication No. 64-25525 (first prior art example and Japanese Utility Model Laid-Open Publication No. 64-25526 (second prior art example) which were proposed by the Applicant's company.
The linear guide apparatus in these prior art examples includes a long guide rail having axially extending ball rolling grooves formed in both side surfaces and a slider movably straddling the guide rail. The slider is composed of a slider main body and end caps respectively joined to opposite ends of the slider main body. The slider main body has ball rolling grooves respectively opposing the ball rolling grooves of the guide rail and has ball return passages respectively disposed in parallel to the ball rolling grooves. On the other hand, each of the end caps is formed with half-doughnut-shaped curved passages respectively connecting a corresponding one of the ball rolling grooves to a corresponding one of the ball return passages of the slider main body. Each of the end caps is also formed with a feed oil passage to supply lubricating oil to the curved passages. Thus, in the slider, infinitely circulating ball routes are formed by the ball rolling grooves, the ball return passages which are in parallel to the ball rolling grooves, and the curved passages which bring the ball rolling grooves into communication with the ball return passages. The slider and the guide rail are moved relative to each other in the axial direction through the rolling of the multiplicity of balls rollably inserted into the infinitely circulating ball routes.
In the end cap in the first prior art example, band-shaped recessed grooves are respectively for-med along the feed oil groove in the lands at both sides of the feed oil groove. Seal members are mounted into the band-shaped recessed grooves to prevent leakage of the lubricating oil from the feed oil groove so as to thereby prevent oil leakage to the outside.
Furthermore, in the end cap in the second prior art example, band-shaped protrusions are integrally formed on the lands at both sides of the feed oil groove to prevent leakage of the lubricating oil from the feed oil groove so as to thereby prevent oil leakage to the outside.
However, in each of the prior art examples, the oil leakage preventing structure in the end cap is only provided on the lands at both sides of the feed oil groove of the end cap. In other words, the recessed grooves are formed and the seal members are mounted therein (first prior example), or the protrusions are integrally formed (second prior example) only in an upper portion of an inverted U-shaped joining surface of the end cap.
As a result, a problem is encountered in which it is impossible to prevent the leakage of the lubricating oil from lower portions of the inverted U-shaped joining surface, that is from both side wall portions of the end cap.